[petsc-users] Compute C*Ct using MatCreateTranspose for Ct

[Olivier Jamond]

Hi all,

I have a rectangle MPIAIJ matrix C. I would like to compute C*Ct 
explicitly to solve some ksp(C*Ct) problems using direct solvers or with 
petsc preconditioners.

If I just create a 'shell' Ct:

Mat Ct;
MatCreateTranspose(C, &Ct);
MatMatMult(C, Ct, MAT_INITIAL_MATRIX, PETSC_DEFAULT, &CCt);

Then it does not work. I get:

[0]PETSC ERROR: No support for this operation for this object type

[0]PETSC ERROR: MatMatTransposeMult not supported for A of type mpiaij

But if instead of C it was Ct that I have explicitly, then it would work:

Mat Ct, CC;
MatTranspose(C, MAT_INITIAL_MATRIX, &Ct);
MatCreateTranspose(Ct, &CC); // create a 'shell' C from explicit Ct to test
MatMatMult(CC, Ct, MAT_INITIAL_MATRIX, PETSC_DEFAULT, &CCt);// this is OK

Is there a way to avoid the explicit transposition of the matrix?

Many thanks,
Olivier Jamond


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